Pontine and medullary respiratory neurons will be recorded in chronic cats during normal sleep-wake cycles. The relationship of the activity of brain stem respiratory neurons to the sleepwake cycle, ponto-geniculo-occipital waves, the development of non-rapid eye movement sleep, vagal afference, the midbrain reticular activating system and various breathing parameters will be analyzed. These studies will provide information on mechanisms of breathing during sleep-wakefulness. This information is essential for an eventual understanding of the clinical sleep apneic syndromes.